Abstract

A time-resolved photoacoustic technique has been applied to the
study of dissolved and dispersed absorbers in aqueous systems. The
temporal pressure profiles generated from colloidal graphite and
glucose solutions were measured, and it was found that the amplitude of
the photoacoustic signal of both the glucose and the colloidal graphite
solutions increase linearly with concentration and that acoustic signal
time delay yields the acoustic velocity. The logarithm of the
photoacoustic signal amplitude changes linearly with the time delay,
with a slope that is proportional to the product of the acoustic
velocity and the optical absorption that can thus be
determined.

Figures (9)

Calculated photoacoustic signals with a one-dimensional
theoretical model. Typical photoacoustic signal of a liquid
generated by laser pulses, dashed curve; and logarithm of the
photoacoustic signal, which is proportional to the time, solid line.

Slope of the logarithm of the photoacoustic signal versus
optical absorption coefficient of colloidal graphite samples. The
optical absorption coefficient was measured with a Shimadzu 3000 NIR
Spectrometer. The solid line represents the best-fit line to that
data.